Retracting finger auger assemblies are well known in the art and have been used for many years to converge crop materials centrally and then feed them rearwardly. Typically, the auger assembly is set up such that the fingers extend as they engage crop material at the front of the auger and retract as they release material at the back.
A typical retracting finger auger assembly has a stationary crank shaft within the auger tube and fingers that are pivotally mounted on an eccentrically offset finger shaft portion of the crank shaft. The auger tube rotates while the crank shaft remains stationary, but because the fingers project outwardly through holes in the auger tube, they are driven around the finger shaft by the auger tube as it rotates. Because the auger tube rotates about one axis while the fingers pivot about the axis of the offset finger shaft, the fingers extend and retract through the holes in the auger tube as they revolve about the finger shaft.
It is known in the art to make such fingers out of a relatively light, tubular steel alloy that is intended to break in the event of untoward loading on the finger such as when striking a rock or other obstruction in the field. However, such tubular fingers tend to break at random locations along their length, or simply bend instead of break off completely and cleanly. Either of such conditions can result in serious damage to the auger tube or the operating mechanism within the auger tube.
Accordingly, it is a goal of the present invention to provide a tubular metal finger that can be relied upon to invariably break off cleanly and completely at a certain, predetermined failure point on the finger when untoward loading is encountered by the finger.